1. Field of the Invention
The present invention is directed to an x-ray radiator of the type having an x-ray tube containing a cathode and an anode in a vacuum housing, an electron beam emanating from the cathode during operation of the x-ray tube which strikes the anode in a focal spot from which x-rays emanate during operation of the x-ray tube, and having a deflection arrangement that deflects the electron beam such that the position of the focal spot on the anode changes as a function of the time.
2. Description of the Prior Art
Such an x-ray radiator of this type is disclosed in U.S. Pat. No. 4,637,040 as a component of a computed tomography (CT) apparatus. The deflection of the electron beam thereby ensues such that the focal spot assumes one of two discrete positions in alternation.
German OS 41 25 926 discloses a deflection means containing a deflection coil that generate a magnetic field for the deflection of the electron beam. The deflector coil is supplied with a current whose time curve corresponds to the desired deflection motion of the focal spot, or of the electron beam. In the case of this x-ray radiator, the speed with which the position of the focal spot can be changed is limited by the inductance of the deflection coil, which acts as a low-pass filter. The result is that the frequency with which the position of the focal spot can be changed is also limited.
U.S. Pat. Nos. 4,819,260 and 4,827,494, and 5,065,420 and 4,803,711 disclose keeping the position of the focal spot of an x-ray tube constant with suitable drive of a deflection means, also with the possibility of adjusting the focal spot to a limited extent. Details as to how the displacement of the focal spot can ensue at high speed, however, cannot be derived from these publications.